The invention relates generally to a Dynamic Data Exchange Server for use in a power management control system and in particular, to a field upgradeable Dynamic Data Exchange Server.
In today's power management control systems, a variety of power monitoring or control devices are connected to a common bus, which allows the power monitoring or control devices to communicate with a server. One standard protocol used for communicating between the server and the power control and monitoring devices is the Modbus RTU standard. Another protocol, Dynamic Data Exchange (DDE), allows independently developed programs to share data and instructions with each other. Using these protocols, the system server can allow external programs to access power management data. There are many Modbus RTU/DDE servers (DDE servers) commercially available for a wide variety of applications. All major electrical distribution companies have a similar product. The narrow scope of these servers is their major limitation. These systems expect the client applications (Human-Machine Interfaces) to handle the complexities of the actual power controlling and metering devices. Many of the servers are designed to communicate using a protocol designed for use with only certain devices, family of devices or specially designed devices. Also, not all the servers are able to support any generic Modbus RTU compliant device.
An improved DDE server is described in U.S. Pat. No. 5,764,155 entitled "Dynamic Data Exchange Server" (the '155 patent). The DDE server described therein provides a mnemonic cross-reference between register items and standardized, alphanumeric parameter names. This mnemonic interface allows the user to retrieve data from a device without knowledge of the actual device register item number. The DDE server acts as a link between a client requesting device data and a field device, which can provide the data. The DDE server communicates to the field device through communication ports and to the client via a DDE or NetDDE message link (Net DDE is an extension of DDE allowing programs running on different computers to share data). A client sends its requests to server to read/write some device registers. The server maps each request to suitable device read/write request packets and carries out the necessary transaction with device. Then it relays the result back to the client after processing and casting the collected device data to proper format.
The DDE server described in the '155 patent is a drastic improvement over those previously known in the art. However, the DDE server of the '155 patent and the DDE servers of the prior art are programmed to serve a particular release of end device firmware. Thus, when end device firmware is upgraded, a new release of DDE server software may be required. Additionally, in order to support a new, generic device type, the register map and mnemonics would have to be manually entered into the DDE server software. The programming required for upgrading the firmware or configuring a new, generic device type results in both time and money costs. In addition, a modification to the DDE server software increases the danger of introducing new software bugs.